Highly Enhanced Cooperative Upconversion Luminescence through Energy Transfer Optimization and Quenching Protection

Abstract

Upconversion luminescence nanomaterials have shown great potential in biological and physical applications because of their unique properties. However, limited research exists on the cooperative sensitization upconversion emission in Tb(3+) ions over Er(3+) ions and Tm(3+) ions because of its low efficiency. Herein, by optimizing the doping ratio of sensitizer and activator to maximize the utilization of the photon energy and introducing the CaF2 inert shell to shield sensitizer from quenchers, we synthesize ultrasmall NaYbF4:Tb@CaF2 nanoparticles with a significant enhancement (690-fold) in cooperative sensitization upconversion emission intensity, compared with the parent NaYbF4:Tb. The lifetime of Tb(3+) emission in NaYbF4:Tb@CaF2 nanoparticles is prolonged extensively to ∼3.5 ms. Furthermore, NaYbF4:Tb@CaF2 was applied in in vitro and in vivo bioimaging. The presented luminescence enhancement strategy provides cooperative sensitization upconversion with new opportunities for bioapplication.

Advances in highly doped upconversion nanoparticles

“…With an inert shell coating, the α-NaYbF 4 :2%Er 3+ @CaF 2 UCNPs display a 15-fold enhancement in visible light emission (Figure 2e ) 47 . Using an inert CaF 2 shell, heavy doping of Yb 3+ ions in the ultra-small α-NaYF 4 :Yb 3+ ,Tm 3+ and α-NaYbF 4 :Tb 3 + nanoparticles was found to dramatically enhance the upconversion emission for high-contrast bioimaging 48 – 51 . With a NaYF 4 inert shell, the optimal concentration of Yb 3+ sensitizer ions was quantitatively examined by characterizing β-phase UCNPs at the single-particle level 52 .…”

Photoluminescent organisms: how to make fungi glow through biointegration with lanthanide metal-organic frameworks

“…S21), we assign this luminescence enhancement to coordination and supramolecular interactions, respectively, of the metal ions and amino acids to mellitate ligands at the surface of the MOF nanoparticles 54–57 . These interactions block the surface luminescence quenching, commonly verified in luminescent nanoparticles 58,59 . In contrast, there is no change in the emission intensity of the Eu-MOF (see Fig.…”

Femtosecond Laser Induced Luminescence in Hierarchically Structured Nd3+,Yb3+,Er3+ Co-Doped Upconversion Nanoparticles: Light-Matter Interaction Mechanisms from Experiments and Simulations

“…We acknowledge that this is still a relatively simple model. More recently, several UCNP photophysical and mechanistic studies [42][43][44][45][46] emphasized the relative importance of specific terms in the kinetic model (or working under specific intensity regimes) that may differ from our implementation. However, given that the main focus of this work is the comparison between experimental and computational CW-and femtosecond-laser induced upconversion, we restrict our study to the effects of power-dependence on population dynamics of the emissive states.…”